Refining of rosin



Filed Jan.V 29, 1943 ..njoou K.

crons: a ARNOLD 'IN ENTQR ls ATTORNEY JLlDW 25.01

Patente-d Aug. 14, 1945 Texas Company, tion, of Delaware,` n:

New York, N. Y., a corpora- ApplicaticnJanuaryzaisla, seria1N0,474,oo7 jI' This invention relates to refining rosin and rosin oils for thepurpose of removing unstable and color forming constituents therefrom.

The invention involves extracting rosin orrosin oil with a solventcomprising water under conditions of elevated temperature and pressureso as to selectively remove color forming .bodies from the rosin. f fWood and gum rosins usually contain substantial amounts ofobjectionablecoloring matterasI well as unstable constituentswhichdevelop into objectionable color .bodies in storageor insubsequentuse. The presence of such latent color. forming bodies isundesired, particularly where the -rosin is employed in the manufactureof high grade soaps and varnishes, etc. i Accordingly, the present'invention hasrrto, do with lan. improved method for extracting lcolorforming bodies from-the rosin. e Advantageously the water extraction isapplied to a solution of the rosin in a suitable solvent having aspecific gravity relatively lower than thatJof water. l

In practicing the inventionrosin oilis dissolved in a suitable solventsuch as gasoline in the proportion of about 5 to 10 parts by volume ofgasoline to 1 part of rosin oil. This solution-is then subjected tocontact with a substantial quantity a stream continuously from the top-of the tower of water `at a temperature in the range about-200 f to 700F. and preferably at about-300 F. While under pressure sufficient tomaintain the mixture in the liquid phase. Under'these conditions coloryThereafter the solvent hydrocarbon can bel stripped from the rosin andrecovered for re-y use. t i l In order to describe the invention inmorede- 2 Claims. (C1. 26o-111) The resulting solution is drawn off througha heating coil or heat exchanger 4 whereinlit is raised to a temperaturelof about 300 to 400 F.

The heated solutionis then introduced to an extraction tower 5advantageously packed with suitable inert packing material adapted tofacili-` tate contact with the water solvent. *j

Astream of Water is continuously introduced to the upper portion vof theextractor througha pipe 6 and to which reference will be made later.

The water introduced at a temperaturelin the range 300 to 400 F.descends overthe packing material within the,tower countercurrentlytothe rising body of rosin solution.- t, l' i The extractor is maintainedunder y-suliicient pressure to keepl the constituents of the mixtureundergoing treatmentin the liquid phasegor at least substantially so.

' Water is introduced to the top'rof the an amount ranging fromabout 1to V4 volumes per volume ofv solvent free rosin 4oil .passing throughtheextractor. f

The extracted rosin oil solutionis drawn 01T- in through a pipe 1. Itis-,cooled duringy passage through a cooler or exchanger .8 after whichitfis dischargedinto a separator 9 which maybe maintained undersubstantially the same pressure as that prevailing within the extractor'5, the-,pressure being controlled by the valves I0 and Il rOn the otherhand the Yseparator may be maintained at a lower A,pressure,a`s for.example, substantially atmospheric pressure, ifde'sired.

The rosinA solution ,entering .the `separator 9 is at a temperature ofVabout 70',t'o.100 F. at which separation intophases occurs, the upperphase comprising rosin solution while thelower phase comprises water.The amount of .water sobbtained is relatively small. Y

tail reference will now be made to the acccmpanyas gasoline is likewisedrawn from a tank Sto the mixer 2.

The vsolvent,V and rosin are introduced in proportion of about 6 or 7parts of solvent to 1 part of rosin and solution of the rosin in thesolventV is effected at a temperature inthe lange about l' 60 to 125 F.

The two phases are separately withdrawn-from the separator 9. Thus, therosin solution lis-cone ducted through a pipe I 2 toa stripper I 3wherein the solvent is stripped -from the i rosin oil, the strippedsolvent being removed through acooler I 4 communicating witha pipelIliby which means solvent may be returned 4to the tank 3..l 1

If desired raillnate recycle may be used togive still better colorremoval. In suchl case a portion of the rosin from stripperr I3 could.be re.- cycled through pipe I6 to theupper part of extractor 5. t Y 1,v

The extract phase accumulating inthe bottom portion of the extractor 5rwhich phase comprises the main body of water containing color. formingbodies, and a minorA amount of rosin dissolved therein' is continuouslywithdrawn through a pipe n with the cooled mixture of water and colorformand cooler 2l. From the cooler 2| it is conducted through a pipe 22to a separator 23.

In the separator 23 the mixture of color forming bodies and a smallamount of rosin and water is subjected to contact with a solvent such asgasoline which is substantially immiscible with The contact is madeunder conditions.`

water. such that the gasoline dissolves the color iorming bodies whichwere removed in the'water lso that the water substantially free from thecolorh forming constituents may be discharged from the system. The colorbodies, after removal-lof" the gasoline, may be discarded or disposedof` otherwise.

As indicated in the drawing the solvent is intrduced through a pipe 25which communicates Again in the' case of the separator 23 the separationof the color forming bodies from the solution in Water may be effectedby scrubbing with the solvent in a countercurrent flow type ofoperation, although the treatment may be carried out in any othersuitable manner.

i In operating a tower extractor such as that illustrated in the drawingit is frequently advantageous to maintain a temperature gradient of toF. throughout the tower,- the bottom portion of the tower being at thelower temperature.

may be accomplished by introducing the water to the top of the extractor5 at a somewhat higher temperature than that at which the rosinfsolution, enters from the heater 4. Inaddition,

the .temperature `conditions throughout the extractor! ina'y'becontrolled to a large extent by with the previously mentioned pipe-22.'rIn this i way the solvent is brought into intimatecontact ing bodies asthe mixture passes through the pipe -22 into the separator .23 which maythus oom-A prise a separating vessel. In such case phase separationoccurs within the separator 23, the lower phase consisting essentiallyof water which can be discharged through a pipe 26 while theupper phasecomprises color `forming bodies dissolved in the hydrocarbon solvent."Ihis upper phase is continuously drawn off through a pipe/21. to astripper 28. In Vthe. stripper 2.8 the solvent is stripped from the`color bodies and the stripped solvent is passed through a cooler 29 andapipe 3U which communicates with the previously mentioned pipe I5'through which the lrecovered solvent is returnedtothe storage tank. Y

The color bodies free from solvent Imay .bedischarged from thestripperthrough a pipe '3.1.

A `portion of the cooled extract phase from` stripper 28 is thusrecycled through abranch pipe 32 tothe extractor 5. The 'lowerportonofthe extractor comprises 'a rectiflow section, the function of which isto realize more eiective separation between color forming "bodiesandro'sin Loil within the reactor. Y Y Y Y i n Y It is contemplated thatseparation between water and color bodies inthe separator 23 may beleffected merely by subjecting the `extract mixture to settling atreduced temperature inthe absence of a solvent such as gasoline. v'In'such case extract recycle material would,.i`f used, be the separatedvcolor bodies. y p y l' As indicated 'the water discharged from theseparator 9 and alsof'from the separator 23 may be returned to a :tank32A tofform'the sourceof i supply for water used in the extractor -l5.In such case the water `is conducted 4vfrornth'e tank f32A through apipe 33 andheater`34 which latter discharges vinto :the previouslymentioned pipe f6.

'Ihe amountof color forming materi'al'and'ros'in discharged from thestripper. 28 'through "the .pipe 3| will depend upon-the :grade of rosinoil undergoing `treatment as we'll'as vupon thejtreating' 'conditions,and may, "for example, amcuntfto Aabout -10to20% 'ofthe rosin oilcharge. .n Y

YItwillfbe understood Athat in 'vpracticing'the invention the methodIol. "flow Aemployed may vary substantially from tthat illustrated inthe drawingl Also the specilicjtype ci apparatus employed at "any stagein the operation umay vary lconsiderably 'from that indicated above.

the amount of yextract recycle or rafnate recycle and the "temperatureat which the extract or raffinate is recycled to the tower.

While gasolinehas been described as a solvent for the solution of therosin oil charge and also for'extractingvthe color bodies from the watersolution, lnevertheless it is contemplated. that other suitable solventsmay be employed for this purpose which are substantially vimmisciblewith water under the conditions prevailing. Other light petroleumdistillates may be employed for this purpose. Likewise the solvent mayconsist essentially of individual petroleum hydrocarbons suchv aspentane, hexane, heptane, etc. It is preferred to employ a gasolinehydrocarbon which Iis substantially free fromv oleflnic and aromatichydrocarbons. u i i v A modification of the-invention involves effectingtreatment of ycrude rosinwvith water under sufficiently elevatedtemperaturev and pressure conditions to dissolve the aforesaidimpurities and in addition the abietic' acid componentoi the rosin. Theresulting solution may then ybe reduced suciently in temperature toeffect crystallization of labietic acid from solution while retainingthe color bodies and other impurities inI solution. The crystallizedacid then may be removed zone, heating it therein to a temperature -ofabout 30G-400 F., thenfpassing the heated stream to the intermediateportion of anextraction col- For example, itheextraction 'carried v'outin `the umn, introducing to the upper lportion of the column, inproportionA relatively large to .said solution stream, a streamconsisting of water 4heated to a temperature of about 3D0-400? F.,subjecting the water and'rosin'so'lution to countercurrent 'contactwithin thel extraction lcolumn under a pressurelsufliciently elevatedtomaintain VAthe mixture undergoing treatment in the liquid phase, forminga raffinate phase comprising rosin solutionand'a minor portion ofthe-Water and an ex- 'trac'tp'h-ase comprising the major portion of thewater containing color Aforming bodies and a mnor amount of rosm;separately discharging .ex- -tractand rainate phases -from the column,substantially Ireducing the temperature of thevdis- Lcharged extractphase, commingling gasoline hydrocarbons with the discharged extractphase such that color forming bodies are dissolved from the water,separating resulting solution of said bodies in hydrocarbons from water,discharging residual water, stripping hydrocarbon solvent from dissolvedextract bodies, discharging stripped solvent, recycling a portion ofresulting solvent-free extract bodies to the lower portion of theextraction tower, discharging extract bodies not so recycled,substantially reducing the temperature of the discharged raflinate phasesuch that Water separates from the rosin solution in gasolinehydrocarbons, discharging the rosin solution from which Water has beenseparated, and recycling at least in part the Water remainingv from boththe raffinate and extract phases to the extraction column.

2. A continuous method for refining rosin to remove color bodiestherefrom which comprises dissolving rosin in gasoline hydrocarbons,passing a stream of said solution through a heating zone, heating ittherein to a temperature of about 30D-400 F., then passing the heatedstream to the intermedaite portion of an extraction column, introducingto the upper portion of the column, in proportion relatively large tosaid solution stream, a stream consisting of Water heated to atemperature of about 30G-400 F., subjecting the Water and rosin solutionto countercurrent contact Within the extraction column under a pressuresufficiently elevated to maintain the mixture undergoing treatment inthe liquidy phase, forming .a ramnate phase comprising rosin solution'and a minor portion of the water and an extract phase comprising themajor portion of the Water containing color forming bodies and a minoramount of rosin, separately discharging extract and raffinate phasesfrom the column, substantially reducing the temperature of thedischarged extract phase, commingling gasoline hydrocarbons With thedischarged extract phase such that color forming bodies are dissolvedfrom thev Water, separating resulting solution of said bodies inhydrocarbons from Water, discharging residual water, strippinghydrocarbon solvent from dissolved extract bodies, discharging strippedsolvent, recycling a, portion of resulting solvent-free extract bodiesto the lower portion of the extraction tower, discharging extract bodiesnot so recycled, substantially reducing the ternvperature of thedischarged raiinate phase such that water separates from the rosinsolution in gasoline hydrocarbons, discharging the rosin solution lfromwhich Water has been separated, separating gasoline hydrocarbons fromthe discharged rosin solution to produce rosin railinate, recycling aportion of said rosin raffinate to the upper portion of the column andrecycling at least a portion of the water remaining from both therafnateand extract phases to the extraction column. I

GEORGE B. ARNOLD.

